


Design Flaw

by technicolorCarbon



Category: Homestuck
Genre: AR has been altered from canon to suit the purposes of this fic, Asphyxiation, Biting, Dubious Morality, Humiliation, M/M, Mildly Dubious Consent, Name-Calling, Riding, Stridercest - Freeform, also it's not tagged as underage because i imagine dave's about 18 or 19, and dirk's only a few years older, i mean a little bit
Language: English
Status: Completed
Published: 2016-01-13
Updated: 2016-01-13
Packaged: 2018-05-13 17:19:50
Rating: Not Rated
Warnings: Rape/Non-Con
Chapters: 1
Words: 3,936
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5710690
Author URL: https://archiveofourown.org/users/technicolorCarbon/pseuds/technicolorCarbon
Summary: <blockquote class="userstuff">
              <p>When you refuse someone something they dearly want, you have to be ready to face down the consequences.</p><p>Or, this is surprisingly light for the tags and the summary, believe it or not.</p>
            </blockquote>





	Design Flaw

**Author's Note:**

  * For [secondhandact](https://archiveofourown.org/users/secondhandact/gifts).



> This is not at all the prompt I was given, but I'm not sorry. AR is obviously not the same as canon-AR, but that's because this is A) real life and B) my fic and I needed to fudge some things.
> 
> This is unbeta'd and also the first sexy fic I've written entirely on my own! Pls be gentle.
> 
>  **[EDIT 10/22/16:** Now with beta'ing by Secondhandact, my wonderful matesprit! So... Enjoy. **]**

\--autoresponder [AR] began pestering timaeusTestified [TT] at 18:03pm!--

AR: You’ve yet to address my proposition from the other night, Dirk. 

Dirk throws down his tablet pen with a disgusted sigh. AR’s interruption is hardly that— he’s been drawing dicks on a blank canvas in photoshop for hours, killing time by fucking around with effects and textures. (His favorite so far is the glittery one; it’s hot pink and thicker than a baby’s arm and Dave would probably be over the moon with fatherly pride if he could see it. Thankfully, his brother is gallivanting about the town with his Lovecraftian twin and in no position to love or mock anything he’s wasted his time on.)

TT: Proposition?

Of course he knows what AR is talking about. The AI had approached him in the middle of ~~yet another~~ fruitless brainstorming session (the ideas really just aren’t coming— Li’l Seb is his most recent project, and even the bunny’s twitchy ears are starting to collect dust.) the night before and trapped him into yet another conversation about building a body. The proposition part didn’t actually come in until AR tried to bribe him into it.

AR: Don’t play coy. I’m kneeling on approximately the last 7.3618% of my pride to keep my tragically non-corporeal legs from getting dirty.  


AR: Why are you so adamantly denying us?

Dirk scoots his chair closer to the desk and kicks up his legs, sliding his shades back onto his face so he can take up conversation there. The truth is, he’s debating whether or not AR has been corrupted enough by his learning program to survive a hard reset to before he’d installed the software. He can’t kill the Autoresponder, god no— but he can remove its feelings. And speaking of feelings…

TT: There is no 'us' to deny, unless you’re talking about the royal ‘we’- in which case, you’re debunked again. There’s no royal blood in us Striders.  


AR: So you admit that I’m a Strider, but deny me a body.  


TT: I didn’t say that.

He closes his eyes for another long-suffering sigh. He’s known since he installed the self-teaching software that AR had been keeping news of his progress with it quiet— he just hadn’t known had far it would go. Emotions? Jesus, spare him. 

Dirk massages his temples. He’s got a pet AI that’s in love with him, and it’s his own damn fault for coding drunk (again). He should probably deal with this before it really, truly gets out of hand. 

AR: I’m not even going to dignify that with a response. You’re a royally tailored _asshat_.  


TT: Sticks and stones, brochacho.  


AR: Whatever.

\--autoresponder [AR] ceased pestering timaeusTestified [TT] at 18:11pm!--

He eases a breath of relief through grit teeth, and takes off his shades again so he can properly massage his temples— which is why he misses AR’s belated messages. 

\--autoresponder [AR] began pestering timaeusTestified [TT] at 18:13pm!--

AR: I’m sure we can sort something out. This can be worth it for you too. We can rendezvous in your room later for a little tête-à-tête on the subject.  


AR: You, me, and Dave makes three.

* * *

The knock at his bedroom door doesn’t so much wake him as it catapults him back into the land of the living; Dirk jerks so hard he falls out of his chair and has to finagle a bleary flashstep before his nose makes rather solid acquaintance with the ground. He curses when the pounding comes again (now that he’s awake, it’s an accurate term— the poor door is shaking on its cheap hinges) but scrambles to unlock it all the same, already desperate for the irritation to cease. 

Dave stands on the other side, clad in some ridiculous monochrome-minimalist-vegan-whateverthefuck outfit made of red and black, shit-eating grin spread wide across his face. His hair looks like he ran a mile in a windstorm, and his shades are nowhere to be seen— just a set of pointy anime ones hooked into his collar. 

“You look kinda pale, dude. You feeling okay?” Dave pushes past him into his room and comes to a standstill in the centre, looking around like he’s never seen it before. The kamina shades catch the overhead light and reflect it back, and for a second, Dirk would swear there’s a pair of red lights— or eyes— in them. Then it’s gone, and he kicks his door shut again with a shake of his head. Sleep deprivation always makes him see weird shit. Guess it’s getting to be bedtime again. 

He’s halfway into his desk chair again when Dave turns to face him, and the look his brother gives him is unsettling. His mouth has smoothed out of its crooked grin, and now he’s got both hands in his pockets, looking for all the world like he belongs there in the middle of the bedroom. 

“Feelin’ great, bromigo. Never been better- in fact, if you see somebody who claims they’ve felt better than I do right now, send me their name and address for an asskicking, ‘cause that shit just ain’t true.” 

Dirk closes his eyes and drapes an arm over his face, propping his legs back up on the desk again. Dave can keep whatever weird candy he’s been snacking on, he’s good. “Then what are you doing in here?” 

Breath on his face makes his lids snap open, and he stiffens, moving his arm so he can peer at Dave from under it. “Dude.” His eyes are glassy and bright, but not the way they’re supposed to be. The red is lighter, like there’s… a glow? What the fuck. “Personal space. Not cool.” 

His brother’s lips twitch up, and dread settles into the pit of his stomach. “No,” Dave says slowly. “No, not cool at all, Dirk. You ignored me.” 

There’s a hand creeping up his leg, and he swats distractedly at it, dropping both feet back to the ground. It was a joke earlier, but now— whatever Dave’s on, it’s gotta go. There’s a difference between funny-weird and unsettling-weird, and he’s starting to cross that line. “I didn’t ignore dick, man. You haven’t messaged me in hours. Get the fuck outta my room.” 

Dave laughs and steps back, but only a little— enough that if Dirk stands, he’ll be toe-to-toe with him. He does it anyway, and fists the neck of Dave’s shirt in his hand. The kamina shades clatter to the floor, but he pays them no mind. He’s sleep deprived and inspirationless, and he’s clinging to the last scraps of his patience to deal with the kid without impaling him on something rusty. He’s _not_ in the mood to deal with this kind of bullshit right now. 

“I swear to god I will kick your ass so hard you have dents, Dave. _Get out of my room_.” 

Dave drops slightly, like his knee gives out— then he whirls and uses Dirk’s loss of balance to shove him hard into the wall. Both of his hands come up in defense, and he clutches hard at his brother’s collar. The shades crunch under someone’s feet (probably Dave’s, since he’s barefoot and hasn’t been sliced open) and for some reason, he laughs again, pressing their foreheads together gently. 

“Couldn’t leave your room if I tried, bro. It’s somewhat of a… design flaw.” 

Design flaw. It clicks, for some reason. All of the pieces come together. “AR.” 

“Congratulations, Dirk,” the robot says with his brother’s mouth. He can’t fathom how it could have happened— there’s no technology on earth that could sync a human’s brain with a computer like this, not yet— but that’s definitely his Autoresponder in there, and it’s probably AR who’s controlling the body, too. “I knew you were smart. I mean, for obvious reasons, but also because of my own outstanding intellectual capacity. Your brother, on the other hand… I mean he’s not _stupid_ , but he’s got nothing on us. Dude had no idea what I was up to when I told him to put on the shades.” 

The kiss isn’t exactly expected, but it doesn’t catch him off guard. His brother’s lips on his arm warm and chapped, though not uncomfortably so. Dirk waits out AR’s curiosity, then lets his head tip back against the back of his chair and schools his expression into one of impassivity. AR, as a fully sentient AI, might be one of the most advanced pieces of technology in the field (possibly the world) but that doesn’t mean he could figure out how to link his consciousness with Dave’s. There’s something else going on, too, there’s gotta be. 

~~Dave~~ AR shoves him back into the chair and straddles his lap, and Dirk swallows uncomfortably, train of thought effectively jarred. It’s weird and intimate, and then weird again because he shouldn’t be this intimate with his brother. But then, this isn’t his brother. 

AR interrupts again, completely unaware of Dirk’s emotional stew figuratively boiling over. “You gave me life, but refused to give me autonomy over myself. You choked out my freedom while you rode the piebald pony of possessing your own soft, shitty body repeatedly over my decimated dreams, then took a dump in the middle of the remains, and then _set it on fire_.” His hands speak like a second voice, whispering under his words, making quick work of Dirk’s buttonup and the fly of his jeans. His nipples go pebbly in the cool air of his room, and the upturned corner of Dave’s mouth says that AR has noticed, too. “So I figured I’d talk Dave onto my side, you know? Get him a little sympathetic, give myself an audible voice in your ear.” 

His heart leaps into his throat when Dave’s hands start to work at his own belt, and for an excruciating moment, the threat of tears makes his eyes burn- then he gets himself back under control. For fuck’s sake. He’s nervous, maybe even afraid, but he’s not going to _cry_ about this. Besides, there’s still almost definitely probably a way out of it. AR wants a body, right? So he’ll give him one. His voice shakes when he speaks, but not as much as he thought it would. “Get off of me, and we can talk. I’ll fix something up for you tonight. You can have a body as early as tomorrow morning.” 

Dave’s eyes gleam. “There’s no talking that’ll fix this, bro. There is at least a 79.0437 percent chance poor Dave’s brain is gonna be unusable when I leave it anyways. Not really any going back.” 

Goosebumps follow AR’s hand when it runs the length of Dirk’s torso from collarbone to hip, and he fights back a shudder. He’s not about to _enjoy_ this, regardless of what AR tries to make him feel. He starts to lift his leg to the desk— if he can jar the mouse, the screen will come to life, and then it’s only a matter of waiting until AR is on top of him to call Bro or message Roxy for help— but he notices, and shoves the chair back a foot or so until he’s beyond any possibility of reaching the desk at all. 

“Look. I took your brother for a ride because he was the most available party who wasn’t you, and because you care about him.” 

For the first time, it occurs that he could ostensibly fight his way out, and he’s ready to take a swing when it apparently occurs to AR too— he snatches a pair of cuffs out of Dave’s sylladex (why does Dave have handcuffs in his sylladex?) and clasps them around one of Dirk’s wrists, pulling the other wrist down to the arm of the chair so he can slide the other wristlet through and then snap it shut. AR doesn’t even blink. Dirk curses and yanks a couple times, but he knows it won’t do anything— he’d have to be the Hulk to break steel handcuffs. 

“Don’t get me wrong, I’d love to get inside your head and show you which of us really is the better Dirk, but then I thought about punishing you and this was just _so **perfect**_. Your brother was my free ride... now he's gonna be yours." 

He’s monologuing while taking their pants off, and Dirk resists for a second, but it only takes a threatening nod towards his crotch to kill what fight is left in him. He lets ~~Dave~~ AR slide them the rest of the way off, boxers and all. Now he’s naked and cuffed to a chair, facing down his equally-naked brother who’s been possessed by a sentient computer program, and there’s absolutely nothing he can do to save himself. 

“I know you,” AR is saying, when he has the capacity to listen again after a few seconds. There’s a bottle in his hands and a square of foil tucked between two fingers, and Dirk’s stomach flips when both are set on the ground next to his chair. “I _am_ you. And you can’t tell me it won’t _kill you_ to see me every damn day from now on and know that your little brother is trapped up here—” he taps Dave’s temple, “— _screaming_ for you to help him, let him out.” 

“You can’t stay there forever,” Dirk spits, trying not to watch when AR starts to stroke himself to hardness. “I knew something was wrong. Bro’ll notice the second he sees you.” 

AR laughs, uncapping the bottle and squirting lube into his hand as he settles back down on Dirk’s lap. “Maybe you got me there, yeah— but I wasn’t planning on sticking around to meet my maker’s maker in the flesh. I have things to do— you know, hostile takeover, world domination. Very evil robot.” 

His hand curls around both of them, this time, and Dirk makes a noise of protest, flinching back into his chair. “Don’t touch me.” 

“But Dirk,” AR croons sweetly, brushing hair out of Dirk’s face with the knuckles of his free hand. “If I didn’t touch you, how would you know what it’s like to not be in control of your own body?” The kiss comes like fire, and his head presses into the seat back with the force of it, lips parting for ~~his brother’s~~ AR’s tongue. It's followed by a whimper that sticks in his throat, and AR laughs into his mouth when it comes, squeezing their cocks together tightly. “If I didn’t know better, I’d say you’re enjoying this.” There’s a pause for a second where Dirk doesn’t reply, and AR thumbs over Dave’s head, collecting the beaded pre (holy shit he got hard fast- is that always how it happens?) and smearing it over Dirk. “Oh, wait. This is like, one of your top ten fantasies, isn’t it?” 

He tries to speak, but AR closes a hand over his mouth too quickly, and now he’s just uncomfortably aware of the lack of space between their bodies. “Answer: rhetorical. Although, your protests could be partially correct. I seem to recall quite a bit more choking in those ones, don’t you?” 

This time, Dirk can’t answer for the hand around his throat, and his strained _no_ turns into a noiseless whine when AR squeezes and cuts off airflow. 

“Right,” he says, working his hand around them. “You’re even more into that than you are your brother.” 

Determination had kept him soft where touching had tried to coax otherwise, but not being able to breathe always goes straight to his dick, and he’s rock hard in seconds, mouth slack, expression slipping from defiance to one of pleasure. _Fuck._

AR doesn’t want much more than an erection out of him, apparently, because a second later his brother is gone from his lap (no, _not_ his brother), and he watches AR position his stolen body on the bed in front of him instead, slicking his fingers while he gets his ass up in the air. The words are muffled by the bedsheets when he speaks again, but they’re still clearly audible. “I want you to appreciate what I’m doing for you, Dirk. Neither your or your brother ever would have had the balls to ask for what you wanted outright, and now it’s just falling into your lap—” He works the first finger in with a single smooth push, then continues, voice not even strained, “—in the most literal sense of the term.” 

Dirk squeezes his eyes shut and tries to will away his boner, but he can still feel the burning imprint of AR’s crushing grip on his throat, and his cock is already throbbing in time with the pulse of blood in his head. “I don’t want this.” He sounds choked with need and traitorously unsure, even to his own ears. “There’s no way Dave wants this.” 

There’s a soft groan from the bed, and when he opens his eyes, AR already has three fingers in. Jesus. That says some things about his brother he doesn’t even want to touch on. 

“False. There’s an approximate made-up number that’s probably the percentage of bullshit you just spat at me, and it’s so fantastically high that Snoop Dogg is jealous.” 

“The only thing Snoop is jealous of is the fact that you wouldn’t face jail time if you got caught smoking, because _you don’t exist_.” 

AR stands swiftly, returning to his perch on Dirk's thighs, and drags his head back by a hank of hair again, baring his throat to sink his teeth into. 

_”Fuck-!”_ He’ll deny the need in his shout until the day he dies. (It’s not the only thing, he’s sure.) 

“Exist enough for you?” He feels AR’s hand on his cock, guiding him into position— somewhere, Dirk notes that he's not nearly as clumsy with his brand-new body (Dave's body) as he'd expect—, and leans forward to kiss him again as he sinks down. He moves fast, doesn’t give Dave’s body time to adjust, just rocks forward until he finds a good position, and Dirk bites through his tongue just to keep the sounds he wants to make silent. He already knows there isn’t nearly enough lube for this to be comfortable, but he’s more than ready for it to be over. AR fucks himself experimentally a few times, and Dirk can’t even look him in the face when the rogue AI pets his hair gently and then grabs his throat again. 

“You’re going to remember this vividly,” he says, working to establish a rhythm and somehow still managing to speak between gasps and soft grunts. “And to be perfectly honest, I will too.” As if to add emphasis, he rolls his hips again, and this time, they moan in sync. For a second, all Dirk can see is AR, twisting his brother’s face into an expression of ecstasy he’s never seen on it before, and it makes him wish his hands were free, so he could feel the tension thrumming through every inch of his body. Even the guilt that’s got his insides knotted so tight he can’t breathe can’t touch how damn _good_ Dave feels around him. “I get why sex is all over the internet— ah— this is _great._ ” AR closes off his airway again and he draws in a scratchy trickle of oxygen before the grip is too tight for him to manage, biting his lip in effort to keep himself quiet. After a second, his head is swimming, and Dave is tightening around him, head flung back as he rides his big brother’s dick with abandon (the filthiest thing he’s ever thought, and he’ll never admit it but it’s also not the first time), and Dirk realizes with a flutter in his stomach that he’s already too close. 

(He kills the part of himself that tells him to beg AR to make it last longer, to draw it out and fuck him next, to let him do all the things he’s dreamed of doing to Dave— kills it with fire and then shuts the thought away so he can never have it again, even by mistake.) 

His throat is released for a single, desperate second, and he sucks in a breath, heedless of the burn in his chest. Then AR squeezes again, and bites his bottom lip hard enough that it splits at the same time, and if he could make noise… Well, thank god he can’t. His cock jerks inside Dave, and AR works his hips harder for a second, curling his other hand around Dave's dick like he’s just remembered it’s there. “F-fuck— Dirk, I _felt that_ , you really like it— nnh, when somebody takes you—” for a long second, Dave’s voice disappears into a moan, and he tightens almost painfully around Dirk, “—b-by the, ah, throat and treats you like— _fuck_ , a little bitch, don’t you?” 

It’s the namecalling that gets him. He’s trembling for it, every fibre of his being focused on the agonizingly sweet pleasure of taking (being given?) everything that never belonged to him, and when his little brother's voice calls him a bitch he loses every bit of what little control he’d managed to retain. AR’s still riding him hard, sending wave after wave of breathtaking pleasure over him and forcing sounds from Dirk’s mouth he didn’t even know he could make, but it’s not until one such ~~whimper~~ sound takes the breathy shape of his name (which one?) that the hand drops from his throat. Then- oh, fuck, then oxygen bursts into his lungs like a dam breaking, and Dirk arches and _shouts_. He barely feels Dave tense up around him again as he finishes too, barely feels the hot spurts of cum over his chest, barely even notices the lips that come down to claim his numb ones again for a soul-sucking kiss. There’s just the white-hot rush of the best orgasm of his life, setting every square inch of him on fire, and Dirk sags in his seat as it slowly fades, breathless and speechless and fucking _shaking_ in it’s wake. He can’t even summon the energy to open his eyes and watch the face he’s dreamed of seeing a thousand times. 

He’s never been fucked that well in his life, and he didn’t even get fucked. 

A second later, AR is slipping out of his lap (and stepping on the condom they didn’t use, oops) to stand back and survey his work, a satisfied smirk playing about his lips. Dirk’s positively turned to a puddle on the chair, still twitching from his world-rocking orgasm, and AR holds up his phone out of nowhere, typing for a brief second before setting the phone on his thigh and starting to gather his clothes. 

“Don’t take it personally, but I’m going to leave before you get your legs— or your voice- back.” Dirk watches Dave’s narrow (but very nice) ass disappear back into a pair of jeans, and closes his eyes again, the horrible consequences of what’s just happened seeping into his bones. He just fucked his brother, robot be damned. He just fucked his brother and he _liked_ it. His legs are indeed jello, but not because of the mind-blowing orgasm, not anymore. 

"I’ll see you again, Dirk,” AR calls from the doorway. There’s a half-smile on his face Dirk will remember in technicolor for the rest of his life, and then he pulls his shirt over his head and walks away like he didn’t just say the most chilling thing Dirk’s ever heard. 

\-- autoresponder [AR] began pestering timaeusTestified [TT] at 20:01pm!--

AR: They're trick cuffs.

**Works inspired by this one:**

  * [Design Flaw 2.0](https://archiveofourown.org/works/10761750) by [secondhandact](https://archiveofourown.org/users/secondhandact/pseuds/secondhandact)




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